In situ growth of defective ZIF-8 on TEMPO-oxidized cellulose nanofibrils for rapid response release of curcumin in food preservation

Abstract

Uncontrolled release of active agents in active packaging reduces antimicrobial efficacy, hindering the effective protection of perishable products from microbial infection. Herein, a novel defective engineering was proposed to design defective and hollow ZIF-8 structures grown on TEMPO oxidized cellulose nanofibrils (TOCNFs) and use them as fast-reacting nanocarriers for loading and controlled release curcumin (Cur) in sodium alginate (SA) active packaging systems (CZT-Cur-SA). By employing stable chelation between tannic acid (TA) and ZIF-8 zinc ions, the connections between zinc ions and imidazole ligands were severed to form a loose and hollow structure, which facilitates the rapid reaction and release of active ingredients triggered by pH changes in the microenvironment. Kinetic tests showed CZT-Cur-SA films released 65.68 % of Cur at pH 6.0 within 24 h, compared to 28.26 % at pH 7.0. These films demonstrated exhibited excellent mechanical properties, antioxidation capacity (82.59 %), reinforced moisture (0.51 × 10⁻¹⁰ g m⁻¹ s⁻¹ Pa⁻¹) and satisfied antimicrobial effects on E. coli (1.69 %) and S. aureus (0.88 %). The optimized CZT-Cur-SA film extended strawberry shelf life to at least 7 days under ambient conditions. Our findings introduce a promising approach to designing responsive, biodegradable active packaging for enhanced food safety.